The present invention is directed to the alignment of optical sensors and, more particularly, is directed to a method and apparatus for visually aligning an optical sensor such as an infrared laser where the laser operates outside the visible spectrum.
The use of optical sensors where the laser operates outside the visible spectrum is common in many industrial applications as well as consumer applications such as hand held remote controllers for TV, stereo etc.
Automated sensing equipment using invisible optical sensors is being increasingly integrated into industrial and manufacturing facilities. A typical example is the overhead infrared (IR) sensing vehicle shown in FIG. 1. This particular vehicle is used to transport semiconductor wafers in an automated clean room semiconductor wafer facility. Each vehicle contains IR sensors which project a three dimensional cone of light. For simplicity, such a three dimensional cone of light will hereafter be referred to as a xe2x80x9cbeamxe2x80x9d. The sensors are used in the safety and guidance of the moving vehicles. Any disruption in the IR beam will stop the motion of the vehicle.
Referring again to FIG. 1, an initial sensor alignment and then periodic alignment checks are currently required to determine proper beam alignment and operation of the unit. A typical unit will utilize an IR light emitting diode (LED), for example, emitting light at a wavelength of approximately 870 nanometers. The human eye is unable to detect this wavelength and therefore reference fixtures or other detectors are required to align the sensors.
This inability to visually monitor the sensor alignment requires that the unit be taken out of normal manufacturing operation for periodic monitoring using fixtures or jigs to check the beam alignment. What is needed is the ability to perform in-situ or real time checks on the sensor beam alignment, while the unit is in normal manufacturing operation, to eliminate costly interruption of the manufacturing operation.
Accordingly, it is a purpose of the present invention to provide an apparatus and method to align an invisible light beam sensor utilizing a visible light beam such as a visible LED or HeNe laser.
It is another purpose of the present invention to provide the ability to align and periodically adjust invisible light beam sensors without fixtures or jigs.
It is another purpose of the present invention to provide the ability to visually monitor when the sensor needs adjustment in real time and avoid off line adjustments.
It is another purpose of the present invention to achieve faster alignment and more repeatable alignments utilizing the visible wavelength.
These and other purposes of the present invention will become more apparent after referring to the following description considered in conjunction with the accompanying drawings.
The purposes and advantages of the present invention have been achieved by providing, according to a first embodiment of the invention an apparatus for performing alignment and monitoring of optical sensors comprising: an invisible light source, such as an infrared or ultraviolet laser, emitting an invisible light beam; a visible light source, such as a Hexe2x80x94Ne laser, emitting a visible light beam and positioned opposite from and approximately coaxial with the invisible light source; an optical polarizing beam splitter having an outer reflecting surface and an inner reflecting surface, the outer reflecting surface reflecting approximately 100% of the invisible light beam and the inner reflecting surface reflecting approximately 50% of the visible light beam in the same path as the invisible light beam, the optical polarizing beam splitter positioned between and approximately coaxial with both the invisible light source and the visible light source; and an optical detector positioned opposite and approximately coaxial with the outer reflecting surface to collect both the reflected invisible and visible light beams.
The apparatus may further comprise a motor connected to the optical beam splitter, which may be rotatable, with a rotatable shaft having a longitudinal opening concentric with its axis of rotation; and the visible light source positioned approximately coaxial with the longitudinal opening.
According to another embodiment of the invention there is provided an apparatus for performing alignment and monitoring of optical sensors comprising: an invisible light source; a visible light source; a reflecting mirror; means for alternatively shuttling the visible light source and the invisible light source in optical alignment with the reflecting mirror, and an optical detector positioned opposite and approximately coaxial with the reflecting mirror.
According to another embodiment of the invention there is provided an apparatus for performing alignment and monitoring of optical sensors comprising: an invisible light source emitting an invisible light beam; a visible light source emitting a visible light beam and positioned opposite and approximately coaxial to the invisible light source; a dual mirror assembly positioned between and approximately coaxial with the visible light source and the invisible light source, the dual mirror assembly having a first side opposite the invisible light source and a second side opposite the visible light source such that in operation the invisible light beam and the visible light beam are both reflected and converge at a common point; a reflecting mirror positioned in alignment with the common point such that both the invisible light beam and the visible light beam are reflected in the same direction; and an optical detector positioned opposite and approximately coaxial with the reflecting mirror to collect both the invisible light beam and the visible light beam.
According to another embodiment of the invention there is provided an apparatus for performing alignment and monitoring of optical sensors comprising: a laser emitting diode having a visible light source and an invisible light source such that the laser emitting diode emits both a visible light beam and an invisible light beam; a reflecting mirror positioned opposite and approximately coaxial with the laser emitting diode; and an optical detector positioned opposite and approximately coaxial with the reflecting mirror to collect both the invisible light beam and the visible light beam.
In one aspect of this embodiment the laser emitting diode is a dual element laser emitting diode which emits a visible laser beam and an invisible laser beam from the same component. In another aspect of this embodiment the light emitting diode is a dual light emitting diode comprising a visible laser source and an invisible laser source positioned adjacent to each other. In another aspect of this embodiment the light emitting diode is a coaxial light emitting diode comprising a visible laser source aligned directly in front of or behind an invisible laser source.
According to another aspect of the invention there is provided a method for performing alignment and monitoring of optical sensors comprising the steps of: providing an invisible light source emitting an invisible light beam; positioning a visible light source emitting a visible light beam opposite from and approximately coaxial with the invisible light source; positioning an optical polarizing beam splitter between and approximately coaxial with the invisible light source and the visible light source, the optical polarizing beam splitter having an outer reflecting surface and an inner reflecting surface, the outer reflecting surface reflecting approximately 100% of the invisible light beam and the inner reflecting surface reflecting approximately 50% of the visible light beam in the same path as the invisible light beam; and positioning an optical detector opposite and approximately coaxial with the outer reflecting surface to collect both the reflected invisible and visible light beams.
The method may further comprise the steps of connecting a motor to the optical beam splitter, which may be rotatable, with a rotatable shaft, the rotatable shaft having a longitudinal opening concentric with its axis of rotation; and positioning the visible light source approximately coaxial with the longitudinal opening.
According to another embodiment of the invention there is provided a method for performing alignment and monitoring of optical sensors comprising the steps of: providing an invisible light source, a visible light source and a reflecting mirror; providing means for alternatively shutting the visible light source and the invisible light source in optical alignment with the reflecting mirror; and positioning an optical detector opposite and approximately coaxial with the reflecting mirror.
According to another embodiment of the invention there is provided a method for performing alignment and monitoring of optical sensors comprising the steps of: providing an invisible light source emitting an invisible light beam; positioning a visible light source emitting a visible light beam opposite and approximately coaxial to the invisible light source; positioning a dual mirror assembly between and approximately coaxial with the visible light source and the invisible light source, the dual mirror assembly having a first side opposite the invisible light source and a second side opposite the visible light source such that in operation the invisible light beam and the visible light beam are both reflected and converge at a common point; positioning a reflecting mirror in alignment with the common point such that both the invisible light beam and the visible light beam are reflected in the same direction; and positioning an optical detector opposite and approximately coaxial with the reflecting mirror to collect the invisible light beam and the visible light beam.
According to another embodiment of the invention there is provided a method for performing alignment and monitoring of optical sensors comprising the steps of: providing a laser emitting diode having a visible light source and an invisible light source such that the laser emitting diode emits both a visible light beam and an invisible light beam; positioning a reflecting mirror opposite and approximately coaxial with the laser emitting diode; and positioning an optical detector opposite and approximately coaxial with the reflecting mirror to collect both the invisible light beam and the visible light beam. The laser emitting diode may be a dual element laser emitting diode which emits a visible laser beam and an invisible laser beam from the same component, a dual light emitting diode comprising a visible laser source and an invisible laser source positioned adjacent to each other, or a coaxial light emitting diode comprising a visible laser source aligned directly in front of or behind an invisible laser source.